Diagnosis:
Maternal screening for NTDs and Down syndrome
• Using the triple screen (i.e., AFP, uE3, and hCG), the detection rate for fetal Down syndrome is 70%, with a false-positive rate of 5%.
• Using the quadratic screen (i.e., AFP, uE3, hCG, and inhibin A), the detection rate for fetal Down syndrome is 81% with a false-positive rate of 5%.
• Calculation of the correct gestational age is important for obtaining accurate risk assessments of Down syndrome. Ultrasound evaluation of the gestational age is now the standard approach.
• The age of the mother is important in calculating the risk of fetal Down syndrome; this risk increases with increasing maternal age.
• In women undergoing assisted reproduction, the age of the egg donor is used to calculate the risk of fetal Down syndrome.
Malone FD, Canick JA, Ball RH, et al:
First-trimester or second- trimester screening, or both, for Down’s syndrome. N Engl J Med 2005;353:2001–2011.
Dugoff L, Hobbins JC, Malone FD, et al:
Quad screen as a predicator of adverse pregnancy outcome. Obstet Gynecol 2005;106:260–267.
